1. Field of Invention
This invention relates to a pen recorder for recording a magnitude of a measured signal with a pen driven in accordance with a digital servo controller.
2. Description of the Prior Art
A conventional pen recorder, which is widely used in a variety of fields, records time variation measured signals on a chart with a pen which moves in accordance with a servo controller on the basis of the value of the measured signal which is converted into an electric signal.
One example of a conventional pen recorder involves a multipen recorder which is constructed with a plurality of pens arranged at given spacings in a direction whereby a chart fed in order to record relatively each of a plurality of measured signals on the chart.
The conventional multipen recorders are classified into two types, the first being an analog technique based recorder and the second being a microprocessor technique based recorder. There are disadvantages to both types, as well as advantages to both types.
The analog technique based recorder is relatively small and simple in operation, and the cost thereof is relatively low. However, disadvantageously, this type of recorder lacks storage capabilities and cannot execute data arithmetic processing.
The microprocessor type recorder is capable of performing multiple digital arithmetic operations and ahieves highly accurate recording results. However, this type of recorder is difficult to miniaturize and is difficult to set measuring and arithmetic conditions therein.
Moreover, with the conventional pen mechanism, it is difficult to select a pen having a suitable pen pressure according to recording velocity. Also, it is impossible to achieve high quality recording when the recording velocity fluctuates sharply.